In a transmission technique, when a failure occurs in a transmission line or at a node, all lines passing through the transmission line or the node having the failure are bypassed to another transmission line or node thereby relieving the lines passing through the failed transmission line or node. In this technique, when an occurrence of a failure is detected at a particular node, switching information as to switching of lines to a detour route is exchanged between this particular node and other nodes. According to the switching information exchanged between nodes, the failed lines are switched to the detour route.
Descriptions of related techniques may be found, for example, in Japanese Laid-open Patent Publication No. 2005-286961.